Alliedsignal Inc.

Promit Das

Terrance R Kinney

A process for analyzing a spectral signal generated by a birefringent element and transmitted to an array. An output spectral signal emanating from the array is converted from an analog to a digital signal to establish a reference wave form which has a dominant frequency after the birefringent element is exposed to a known temperature. Thereafter, a current wave form is generated from the output spectral signal emanating from the array. A phase and frequency relationship is obtained by cross correlating the current wave form and the reference wave form. The dominant frequency for the phase and frequency relationship is obtained by Fast Fourier Transformation. Thereafter, the dominant frequency for the phase and frequency relationship of the current wave form is compared with the dominant frequency for the reference wave form to determine a temperature range. The temperature range and phase and dominant frequency for the current wave form are matched with a reference schedule stored in the memory of a digital signal processor to predict the current temperature experienced by the birefringent element. This predicted temperature is displayed on a screen to inform an operator of the current operational conditions experienced by the birefringent element.

Spectral signal analyzer system

A light off detecting arrangement for sensing the presence of a flame in a region such as the afterburner of a turbine engine is disclosed. An optical focusing device such as a lens or mirror is located near a quartz window adjacent the afterburner for concentrating electromagnetic radiation emanating from the region. An optical (fiber optic) pathway receives the concentrated electromagnetic radiation from the optical focusing device and conveys that radiation thru the optic filters to an opto-electrical converter for converting incident electromagnetic radiation to electrical signals. A frequency selective optical device such as an infrared filter is interposed between the optical focusing device and the opto-electrical converter for insuring that a preselected portion only of the electromagnetic radiation emanating from the region is converted to electrical signals. The electrical signals are compared to a predetermined threshold value and a fault flame present indication is issued if the comparison indicates sufficient radiation in the preselected portion indicative of the presence of a flame, and a second no flame indication is issued otherwise.

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South Bend, IN, United States of America

Promit Das